Multiplex communications – Pathfinding or routing – Through a circuit switch
Reexamination Certificate
1998-02-11
2001-04-10
Olms, Douglas W. (Department: 2661)
Multiplex communications
Pathfinding or routing
Through a circuit switch
C370S338000, C370S401000, C370S420000
Reexamination Certificate
active
06215785
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to methods and apparatus for communicating across a computer network. More particularly, the present invention relates to methods and apparatus for efficiently communicating across a digital subscriber loop (DSL).
2. Description of the Relevant Art
As computer usage becomes increasingly prevalent, the ability to share resources between computers has also increased. Computer systems at many different locations are often linked by a network such that information may be shared between the computer systems, e.g., data may be transferred between the computer systems.
Many different protocols may be used to transfer data between computer systems. By way of example, some protocols include an integrated services digital network (ISDN) and a digital subscriber loop (DSL), which are well known to those skilled in the art. Recently, due to the popularity of the Internet, as the volume of data which is transferred between computer systems increases, the demand for the ability to transfer large volumes of information in relatively short periods of time is growing. Accordingly, DSL technology is constantly being improved to address growing demands.
Subscriber loops, as for example DSLs, are commonly used to enable computers to communicate over a network.
FIG. 1
is a diagrammatic representation of different subscriber loops in communication with a wide area network (WAN) in accordance with prior art. WAN
104
is essentially the network over which various entities
108
a-d
are allowed to communicate in order to transfer data. Entities
108
a-d
may generally include small customers, which are often “residences,” e.g., residence customer
108
a
, that have computer systems and/or entertainment systems that are linked to WAN
104
. Entities
108
a-d
may also include large customers or “businesses,” e.g., business customer
108
c
, which have computer systems that are in communication with WAN
104
.
Business customer
108
c
may often require bi-directional high speed data transfer. By way of example, business customer
108
c
may need to readily access and update databases located in WAN
104
. As such, business customer
108
c
is typically linked to WAN
104
using data lines which are capable of supporting bi-directional high speed data transfer. A T
1
line
112
may be used to link business customer
108
c
to a node
116
within WAN
104
. T
1
line
112
has a data transfer rate of up to approximately 1.544 megabits-per-second (Mbps), and uses a single wire to bi-directionally transfer data.
As shown, a high speed DSL (HDSL) line
120
may be used to link business customer
108
c
to a node
124
within WAN
104
. HDSL line
120
, like T
1
line
112
, has a data transfer rate of up to approximately 1.544 Mbps. However, for reliability purposes, HDSL line
120
includes two bi-directional lines which transfer data between node
124
and business customer
108
c.
Another type of communications link, an integrated DSL (IDSL), is created when ISDN technologies are applied to DSL. An IDSL line is capable of bi-directionally transferring data at rates of up to approximately 128 Kbps, which is typically sufficient for transmitting voice information between touch-tone (TT) phones. A first IDSL line
136
may be used to connect a TT phone associated with an entity, e.g., residence customer
108
b
, across WAN
104
, to a TT phone associated with another entity, e.g., residence customer
108
d
, which is connected to a second IDSL line
140
. When voice data is to be transmitted from residence customer
108
b
to residence customer
108
d
, the voice data is transmitted in analog form across IDSL line
136
, which is a copper wire, to a node
144
where the voice data is digitized. The digitized voice data is then routed over WAN to another node
146
, where the digitized voice data is converted back into analog form, and sent over IDSL line
140
to residence customer
108
d.
Residence customer
108
a
, unlike business customer
108
c
, may not require bi-directional high speed data transfer, due to that fact that residence customer
108
a
is typically more likely to download information, e.g., video data for video-on-demand technologies, through WAN
104
than to upload information through WAN
104
. Accordingly, residence customer
108
a generally uses an asymmetric DSL (ADSL) connection
128
which includes a “downloading” line that is arranged transfer data downloaded from a node
132
, or a central office port, to residence customer
108
a
at rates of up to approximately 8 Mbps. ADSL connection
128
also includes an “uploading” line which is arranged to transfer data uploaded from residence customer
108
a
to node
132
at rates of up to approximately 384 kilobytes-per-second (Kbps).
In general, an IDSL connection is considered to be sufficient to transfer voice data between TT phones because the volume of data transfer is relatively low. However, in order to transfer data relating to the Internet, e.g., World Wide Web pages and video-on-demand data, to Internet customers such as residence customers, an ADSL connection is typically preferred over an IDSL connection. Internet usage typically involves downloading information to a computer system, as for example a computer system associated with the residence customer. Hence, since an ADSL connection is arranged to provide the capability to quickly download relatively high volumes of data to a computer system, while still enabling data to be uploaded from the computer system when necessary, an ADSL connection is particularly suitable for use by customers who generally download data.
Although an ADSL connection is effective for use in transferring data over the Internet, an ADSL connection typically requires a dedicated node, e.g., a dedicated central office port with an ADSL card, as well as dedicated power for each Internet customer.
FIG. 2
is a diagrammatic representation of conventional point-to-point ADSL connections to a central office (CO). As shown, a system with point-to-point ADSL connections
202
includes customers
204
a-l
, e.g., residences, which are each linked to a central office
206
via ADSL connections
210
a-l
. Specifically, customers
204
a-l
are linked via ADSL connections
210
a-l
to dedicated ports
214
a-l
associated with central office
206
.
Each customer
204
a-l
generally has a point-to-point ADSL card which is connected to an appropriate ADSL connection
210
a-l
. The appropriate ADSL connection
210
a-l
is connected to a point-to-point ADSL card at central office
206
(not shown) which is associated with an appropriate port
214
a-l
. ADSL cards include point-to-point ADSL cards, such as those which are available commercially from Interphase Corporation of Dallas, Texas.
An ADSL connection, as for example ADSL connection
210
a
is generally comprised of a copper twisted pair over which data is transmitted downstream to customer
204
a
, and upstream from customer
204
a
to central office
206
. Due to the fact that availability of copper wire is relatively fixed in the current communications network infrastructure, and, further, that separate ports, such as port
214
a
, are required for each customer
204
a-l
, the implementation of point-to-point ADSL is often expensive.
Since data transferred over the Internet is bursty data, as will be appreciated by those skilled in the art, ADSL connections, e.g., ADSL connections
210
a-l
, are not active, or in use, much of the time. Therefore, as the full bandwidth associated with the ADSL connections is largely unused, resources associated with the ADSL connections are often essentially wasted. Further, as the length of an ADSL connection increases, the effective data transfer rate decreases. In other words, as the distances between a central office and an Internet customer increases, the data transfer rate across an ADSL connection between the central office and the customer decreases. As a result, while ADSL connections may transfer data at rates of betwe
Batruni Roy G.
Bhardwaj Vinod K.
Beyer Weaver & Thomas LLP
ControlNet, Inc.
Hom Shick
Olms Douglas W.
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